The present invention relates to perfluoroelastomers having a very good combination of mechanical properties, compression set and at low temperature properties and to the process for preparation thereof.
It is well known that perfluoroalkylvinylethers are generally used as monomers for the copolymerization with tetrafluoroethylene (TFE) to obtain perfluoroelastomers which are used in the space-, oil-, petrochemical and semiconductor industry. The introduction of perfluorovinylether high amounts in crosslinkable fluoroelastomers implies elasticity properties at low temperature of fluorinated rubbers.
The need was felt to have available perfluoroelastomers having improved properties at low temperatures in combination with good mechanical and compression set properties.
To solve said technical problem fluorovinylethers with various structural properties have been proposed in the prior art. However from the prior art the obtained perfluoroelastomers do not show the combination of the above properties.
U.S. Pat. No. 3,132,123 describes the preparation of perfluoroalkylvinylethers, of the respective homopolymers and copolymers with TFE. The homopolymers are obtained under extreme experimental conditions, by using polymerization pressures from 4,000 to 18,000 atm. The homopolymer of the perfluoromethylvinylether (MVE) is an elastomer: however its Tg is not sufficiently low. The general formula of the described vinylethers is the following:
CF2xe2x95x90CFOR0F
wherein R0F is a perfluoroalkyl radical preferably from 1 to 5 carbon atoms.
U.S. Pat. No. 3,450,684 relates to vinylethers of formula:
CF2xe2x95x90CFO(CF2CFX0O)nxe2x80x2CF2CF2X0
wherein X0xe2x95x90F, Cl, CF3, H; nxe2x80x2 can range from 1 to 20.
Homopolymers obtained by UV polymerization are also described. The exemplified copolymers are not characterized with their mechanical and elastomeric properties at low temperatures.
U.S. Pat. No. 3,817,960 relates to the preparation and polymerization of perfluorovinylethers of formula:
CF3O(CF2O)nxe2x80x3CF2CF2OCFxe2x95x90CF2
wherein nxe2x80x3 can range from 1 to 5. Characterization data on the above properties are not described.
U.S. Pat. No. 4,487,903 relates to the fluoroelastomeric copolymer preparation wherein perfluorovinylethers of formula:
CF2xe2x95x90CF(OCF2CFY0)n0OX2
are used, wherein n0 ranges from 1 to 4; Y0xe2x95x90F, Cl, CF3, H; X2 can be C1-C3 perfluoroalkyl, C1-C3 xcfx89-hydroperfluoroalkyl, C1-C3 xcfx89-chloroperfluoroalkyl. The polymer has a fluorovinylether unit content ranging from 15 to 50% by moles. Said vinylethers give copolymers having at low temperatures properties superior to those of the above perfluorovinylethers of PVE (perfluoropropylvinylether) and MVE type. Also in this case data relating to the above properties of the cured elastomer are not indicated.
EP 130,052 describes the polymerization of the perfluorovinylpolyethers (PVPE) which leads to the obtainment of amorphous perfluoropolymers having a Tg ranging from xe2x88x9215xc2x0 to xe2x88x92100xc2x0 C. The described polymers have Tg values which reach xe2x88x9276xc2x0 C.; the further Tg decrease is obtained by using perfluoropolyethers as plasticizers. In the patent copolymers and terpolymers of TFE and MVE with vinylethers (PVPE) of formula:
CF2xe2x95x90CFO(CF2CF(CF3)O)nxe2x80x2xe2x80x3R0fxe2x80x2
are described, wherein nxe2x80x2xe2x80x3 ranges from 3 to 30 and R0fxe2x80x2 is a perfluoroalkyl. Due to purification difficulties, the used vinylethers are mixtures of vinylethers with different values of nxe2x80x2xe2x80x3. According to this patent the most marked effect on the Tg decrease is shown when nxe2x80x2xe2x80x3 is equal to or higher than 3, preferably higher than 4.
U.S. Pat. No. 4,766,190 relates to the polymerization of perfluorovinylpolyethers (PVPE), similar to those described in U.S. Pat. No. 4,487,903, with TFE and low percentages of perfluoro propene, to increase the mechanical properties of the obtained polymers. No improvement of the mechanical and elastomeric properties at low temperatures is described.
U.S. Pat. No. 5,268,405 discloses the preparation of perfluorinated rubbers having a low Tg, by using perfluoropolyethers having a high viscosity as plasticizers of perfluorinated rubbers (TFE/MVE copolymers). The obtained manufactured articles have the drawback that during the use, exudations of the perfluoropolyethers (PFPE) take place, in particular when PFPE has low molecular weight (low viscosity): in the patent it is therefore disclosed the use of PFPE having high viscosity; those having low viscosity must be previously removed.
U.S. Pat. No. 5,401,818 relates to the perfluorovinylether preparation of formula:
R1f(OCF2CF2CF2)mxe2x80x2xe2x80x94OCFxe2x95x90CF2
(wherein R1f is a C1-C3 perfluoroalkyl radical; mxe2x80x2 is an integer raanging from 1 to 4) and of the respective copolymers having improved properties at low temperature. The preparation of said perfluorovinylethers requires also a perfluorination with elementary F2 which from the industrial point of view requires supplementary process unities.
Furthermore it is well known that by increasing the perfluorooxyalkylene units which are part of the side perfluorooxyalkylene substituent of perfluorooxyalkylvinylethers, the Tg of the obtained amporphous copolymers decreases. However it is not possible to obtain polymers with the optimal combination of the above properties.
The amorphous copolymers of TFE with perfluoromethylvinylether have Tg of about 0xc2x0 C. or a little lower (Maskornik, M. et al. xe2x80x9cECD-006 Fluoroelastomerxe2x80x94A high performance engineering materialxe2x80x9d. Soc. Plast Eng. Tech. Pao. (1974), 20, 675-7). The extrapolated value of the MVE homopolymer Tg is of about xe2x88x925xc2x0 C. (J. Macromol. Sci.-Phys., B1(4), 815-830, December 1967).
In patent application EP 1,148,072 fluorovinylethers allowing to lower the Tg of the respective copolymers are described, but the mechanical and elastomeric properties of the obtained manufactured articles are not described.
The perfluoroelastomers described in the prior art do not show the optimal combination of the above properties, in particular it would be desirable to have available perfluoroelastomers which when cured show the following combination of properties:
good mechanical and elastomeric properties,
high resistance to low temperatures such as for example shown by TR 10 (ASTM D 1329 method),
much lower Tg with respect to vinylethers having the same oxygen number and carbon atoms,
maintenance of good mechanical and elastomeric properties even at high temperatures to have a high thermal range of the perfluoroelastomer use,
higher productivity of perfluoroelastomer in Kg of polymer/(hourxc3x97liter of water).
The Applicant has surprisingly and unexpectedly found that it is possible to solve the above technical problem as described hereinafter.
An object of the present invention are perfluoroelastomers, curable by peroxidic route, obtainable by polymerizing the following monomers:
a) tetrafluoroethylene (TFE);
b) fluorovinylethers of general formula:
CFXxe2x95x90CXOCF2ORxe2x80x83xe2x80x83(I)
xe2x80x83wherein
R has the following meanings:
C2-C6 linear or branched (per)fluoroalkyl,
C5-C6 cyclic (per)fluoroalkyl,
C2-C6 linear or branched (per)fluoro oxyalkyl, containing from one to three oxygen atoms,
Xxe2x95x90F, H;
c) bis-olefins having general formula:
RI1RI2Cxe2x95x90CRI3xe2x80x94Zxe2x80x94CRI4xe2x95x90CRI5RI6xe2x80x83xe2x80x83(IA)
xe2x80x83wherein
RI1, RI2, RI3, RI4, RI5, RI6 equal to or different from each other, are H or C1-C5 alkyl;
Z is a C1-C18 linear or branched alkylene or C4-C18 cycloalkylene radical, optionally containing oxygen atoms, preferably at least partially fluorinated, or a (per)fluoropolyoxyalkylene radical;
d) optionally, one or more fluorinated olefinic comonomers selected from the following:
C3-C8 perfluoroolefins, such hexafluoropropene (HFP), and/or chlorotrifluoroethylene (CTFE);
perfluoroalkylvinylethers (PAVE) CF2xe2x95x90CFOR2fxe2x80x2 wherein R2f is a C1-C6 perfluoroalkyl, for example trifluoromethyl, heptafluoropropyl;
perfluoro-oxyalkylvinylethers CF2xe2x95x90CFOXa, wherein Xa is a C1-C12 alkyl, or a C1-C12 oxyalkyl, or a C1-C12 (per)fluoro-oxyalkyl having one or more ether groups, for example perfluoro-2-propoxy-propyl;
said perfluoroelastomers comprising halogen atoms selected from iodine and/or bromine in the chain and/or in end position, said iodine and/or bromine atoms deriving from xe2x80x9ccure sitexe2x80x9d comonomers and/or from chain transfer agents used in polymerization.
The preferred fluorovinylethers component b) are those of general formula:
CFXxe2x95x90CXOCF2OCF2CF2Yxe2x80x83xe2x80x83(II)
wherein Yxe2x95x90F, OCF3; X as above.
The perfluorovinylethers of formula:
CF2xe2x95x90CFOCF2OCF2CF3xe2x80x83xe2x80x83(MOVE 1)
CF2xe2x95x90CFOCF2OCF2CF2OCF3xe2x80x83xe2x80x83(MOVE 2)
are the most preferred.
Preferably in the bis-olefin component c) of formula (IA) RI1, RI2, RI3, RI4, RI5, RI6are hydrogen and Z is a C4-C12 perfluoroalkylene radical or a (per)fluoropolyoxyalkylene radical of formula:
xe2x80x94(Q)pxe2x80x94CF2Oxe2x80x94(CF2CF2O)ma(CF2O)naxe2x80x94CF2xe2x80x94(Q)pxe2x80x94xe2x80x83xe2x80x83(IIA)
wherein:
Q is a C1-C10 alkylene or oxyalkylene radical, preferably selected from xe2x80x94CH2OCH2xe2x80x94; xe2x80x94CH2O(CH2CH2O)sCH2xe2x80x94, s being=an integer from 1 to 3;
p is an integer and is zero or 1;
ma and na are numbers such that the ma/na ratio is from 0.2 to 5, the molecular weight of the (per)fluoropolyoxyalkylene radical of formula (IIA) being from 500 to 10,000, preferably from 1,000 to 4,000. More preferably the bis-olefin has formula:
xe2x80x83CH2xe2x95x90CHxe2x80x94(CF2)t0xe2x80x94CHxe2x95x90CH2
wherein t0 is an integer from 6 to 10 carbon atoms.
The iodine and/or bromine atoms in the chain and/or in end position of the polymer can be introduced by brominated and/or iodinated xe2x80x9ccure sitexe2x80x9d comonomers, such for example the following:
C2-C10 bromo and/or iodo olefins, containing at least one atom, preferably from one to three bromine and/or iodine atoms,
C1-C10 linear or branched (per)fluoroalkylvinylethers and/or (per)fluorooxyalkylvinylethers containing at least one iodine and/or bromine atom.
The iodine and/or bromine atom in the polymer end position can be introduced also using iodinated and/or brominated chain transfer agents, such as for example the following:
compounds of formula Rbf(I)x(Br)y, wherein Rbf is a (per)fluoroalkyl or a (per)fluorochloroalkyl having from 1 to 8 carbon atoms, while x and y are integers comprised between 0 and 2, with 1xe2x89xa6x+yxe2x89xa62;
iodides and/or bromides of alkaline or alkaline-earth metals.
Preferably the perfluoroelastomer contains iodine atoms in the chain and/or in end position.
The preferred optional component d) is perfluoromethylvinylether (MVE) having formula CF2xe2x95x90CFxe2x80x94Oxe2x80x94CF3.
As said, the perfluoropolymers of the invention show the combination of the above properties.
In particular the decrease of Tg obtained by using the vinylethers component b) is due to the presence of the (xe2x80x94OCxe2x80x94F2O) unit directly linked to the unsaturation. Besides it has been found that said unit increases the reactivity of the vinylether component b).
The advantages of the perfluoroelastomers of the invention can be summarized as follows:
improved mechanical and elastomeric properties;
very good reactivity of the fluorovinylethers component b), in Kg of polymer/(hour liter of water);
low Tg;
low TR 10.
The amount of fluorovinylethers component b) to obtain the perfluoroelastomers of the invention must be such to lead to the crystalline site disappearance so to obtain an amorphous copolymer.
Generally the amount of units deriving from the fluorovinylether component b) which allows to obtain amorphous polymers is preferably higher than 15% by moles, more preferably higher than 20% by moles. There are no limits to the maximum amount of b): molar amounts up to 80-90% can generally be used. If in the polymer, besides units deriving from the fluorovinylether component b), units deriving from the optional monomers component d) are present, the total molar amount of b)+d) must be higher than 15%, preferably higher than 20% by moles. The total amount of b)+d) can reach percentages of 80-90% by moles.
The amount of units in the chain deriving from the bis-olefin component c) is generally from 0.01 to 2.0% by moles, preferably from 0.05 to 0.8% by moles.
The amount of units deriving from brominated and/or iodinated xe2x80x9ccure-sitexe2x80x9d comonomers in the final compound is from 0 to 5% by moles.
The iodine and/or bromine amount from transfer agent present in the chain end groups is from 0% to 2% by weight, preferably from 0.05% to 0.8% by weight.
The total amount of iodine and/or bromine present in the perfluorinated polymer is in the range 0.05%-4% by weight.
The perfluoroelastomers of the invention are TFE-based copolymers, wherein TFE is copolymerized with the fluorovinylethers component b) and with the bisolefin component c); wherein also one or more comonomers selected from component d) can optionally be present.
The preferred monomeric compositions (% by moles) are the following:
the sum of the molar percentages of component b)+component d) being such to give an amorphous polymer, said sum being higher than 15%, preferably higher than 20%, and the sum of the molar percentages of the monomers being equal to 100%.
The bis-olefins component c) of formula (IA) wherein Z is an alkylene or cycloalkylene radical can be prepared as for example described by I. L. Knunyants et al. in Izv. Akad. Nauk. SSR, Ser. Khim. 1964(2), 384-6, while the bis-olefins containing (per)fluoropolyoxyalkylene sequences are obtainable by following the reactions reported in U.S. Pat. No. 3,810,874.
The brominated and/or iodinated xe2x80x9ccure-sitexe2x80x9d comonomers are for example described in U.S. Pat. Nos. 4,035,565 and 4,694,045, 4,745,165, 4,564,662 and EP 199,138.
For the iodinated and/or brominated chain transfer agents see for example U.S. Pat. Nos. 4,243,770 and 4,943,622.
For the chain transfer agents formed by iodides and/or bromides of alkaline or alkaline-earth metals see U.S. Pat. No. 5,173,553.
The preparation of perfluoroelastomers of the present invention is carried out by copolymerization of the monomers in aqueous emulsion in the presence of an emulsion, dispersion or microemulsion of perfluoropolyoxyalkylenes, according to U.S. Pat. Nos. 4,789,717 and 4,864,006. Preferably the synthesis is carried out in the presence of perfluoropolyoxyalkylene microemulsion.
According to well known methods of the prior art, radical initiators, for example, alkaline or ammonium persulphates, perphosphates, perborates or percarbonates, optionally in combination with ferrous, cupreous or silver salts, or of other easily oxidizable metals, are used. In the reaction medium also surfactants of various type are optionally present, among which the fluorinated surfactants of formula:
R3fxe2x80x94Xxe2x88x92M+
are particularly preferred, wherein R3f is a C5-C16 (per)fluoroalkyl chain or a (per)fluoropolyoxyalkyl chain, Xxe2x88x92 is xe2x80x94COOxe2x88x92 or xe2x80x94SO3xe2x88x92, M+ is selected from: H+, NH4+, an alkaline metal ion. Among the most commonly used we remember: ammonium perfluorooctanoate, (per)fluoropolyoxyalkylenes ended with one or more carboxyl groups, etc. See U.S. Pat. Nos. 4,990,283 and 4,864,006.
The polymerization reaction is generally carried out at temperatures in the range 25xc2x0 C.-150xc2x0 C., at a pressure comprised between the atmospheric one up to 10 MPa.
Alternatively or in combination with the chain transfer agents containing iodine and/or bromine, other chain transfer agents known in the prior art, as ethyl acetate, diethylmalonate, etc., can be used.
When the polymerization is over, the perfluoroelastomer is isolated from the emulsion by conventional methods, as the coagulation by addition of electrolytes or by cooling.
The perfluoroelastomers object of the present invention are cured by peroxidic route, according to known techniques, by addition of a suitable peroxide capable to generate radicals by heating.
Among the most commonly used peroxides the following are mentioned: dialkylperoxides, such for example, di-terbutyl-peroxide and 2,5-dimethyl-2,5-di(terbutylperoxy)hexane; di-cumyl peroxide, dibenzoyl peroxide; diterbutyl perbenzoate; di-[1,3-dimethyl-3-(terbutylperoxy)butyl]carbonate. Other peroxidic systems are described for example in European patent applications EP 136,596 and EP 410,351.
To the curing blend other compounds are then added, such as:
(A) curing coagents, in an amount generally in the range 0.5-10%, preferably 1-7%, by weight with respect to the polymer; among them those commonly used are: bis-olefins of formula (IA); triallyl-cyanurate, triallyl-isocyanurate (TAIC), tris(diallylamine)-s-triazine; triallylphosphite; N,N-diallyl-acrylamide; N,N,Nxe2x80x2,Nxe2x80x2-tetraallyl-malonamide; tri-vinyl-isocyanurate; and 4,6-tri-vinyl-methyltrisiloxane, etc.: TAIC and the bis-olefin of formula:
CH2xe2x95x90CHxe2x80x94(CF2)6xe2x80x94CHxe2x95x90CH2
are particularly preferred;
(B) optionally a metal compound, in an amount in the range 0-15%, preferably 2-10%, by weight with respect to the polymer, selected from oxides and hydroxides of divalent metals, such for example Mg, Zn, Ca or Pb, optionally combined with a weak acid salt, such for example stearates, benzoates, carbonates, oxalates or phosphites of Ba, Na, K, Pb, Ca;
(C) optionally acid acceptors, in an amount from 0 to 10% by weight with respect to the polymer, of the non metal oxide type, such 1,8 bis dimethyl amino naphthalene, octadecylamine etc. as described in EP 708,797;
(D) optionally conventional additives, such thickeners, pigments, antioxidants, stabilizers and the like, the amount of each of said additives being between 0 and 10% by weight with respect to the polymer;
(E) optionally fillers in amounts from 0 to 80% by weight with respect to the polymer, preferably from 15 to 50% by weight, such for example carbon black, silica, barium sulphate, titanium dioxide, etc. Fillers of semicrystalline fluoropolymers, such PTFE, MFA and PFA, can also be present.
The copolymers of the invention when cured by peroxidic route show a very good combination of properties, in particular they satisfy the following test: a copolymer having the following composition in per cent by moles:
having as attack site for the peroxidic crosslinking an iodine amount, in per cent by weight, equal to 0.24%, the iodine being present on the chain end groups through the iodinated transfer agent 1,4-diiodoperfluorobutane (C4F8I2), in a compound containing for 100 phr of perfluoroelastomer:
cured in press for 10 minutes at 160xc2x0 C., subjected to post-cure in an air forced circulation stove at 230xc2x0 C. for 4 hours, after a warming step from room temperature to 230xc2x0 C. lasting one hour, shows the following combination of properties:
The synthesis process of the (per)fluorovinylethers component b) comprises the following steps:
axe2x80x2) initial reaction of the hypofluorite with a fluorinated olefin of formula R1R2Cxe2x95x90CR3R4 to give the hypofluorite
CF2(OF)2+R1R2Cxe2x95x90CR3R4xe2x86x92Fxe2x80x94CR1R2xe2x80x94CR3R4xe2x80x94OCF2OFxe2x80x83xe2x80x83(VI)
bxe2x80x2) reaction of the hypofluorite with a second fluorinated olefin of formula R5R6Cxe2x95x90CR7R8 to give the intermediate
Fxe2x80x94CR1R2xe2x80x94CR3R4xe2x80x94OCF2Oxe2x80x94CR5R6xe2x80x94CR7R8xe2x80x94F, Fxe2x80x94CR1R2xe2x80x94CR3R4xe2x80x94OCF2OF+R5R6C2xe2x95x90C1R7R8xe2x86x92Fxe2x80x94CR1R2xe2x80x94CR3R4xe2x80x94OCF2Oxe2x80x94C2R5R6xe2x80x94C1R7R8xe2x80x94Fxe2x80x83xe2x80x83(VII)
cxe2x80x2) dehalogenation or dehydrohalogenation and obtainment of the perfluorovinylethers. 
In said synthesis scheme:
with reference to the formula of compound (VII):
R1, R4, equal or different, are H, F; R2, R3, equal or different are H, Cl at the following conditions: (1) when the final reaction is a dehalogenation R2, R3=Cl, (2) when the final reaction is a dehydrohalogenation one of the two substituents R2, R3 is H and the other is Cl;
R5, R6, R7, R8 are:
F, or one of them is a C1-C4 linear or branched perfluoroalkyl group, or a C1-C4 linear or branched perfluorooxyalkyl group containing from one to three oxygen atoms, or R5 and R7, or R6 and R8, are linked each other to form with C2 and C1 a C5-C6 perfluoroalkyl cycle;
when one of the radicals R5 to R8 is a C2-C4linear or branched fluoroalkyl, or a C2-C4 linear or branched fluorooxyalkyl containing from one to three oxygen atoms, one or two of the other R5 to R8 are F and one or two of the remainders, equal to or different from each other, are selected from H, Cl; when the substituents selected from H and Cl are two, they are both linked to the same carbon atom;
when R5 and R7, or R6 and R8, are linked each other to form with C2 and C1 a C5-C6 fluoroalkyl cycle, one of the two free substituents R6, R8 or R5, R7 is F and the other is selected from H, Cl.
the fluoroalkene used in the reaction axe2x80x2) is replaceable with that of the subsequent reaction bxe2x80x2); in this case the meanings defined for the substituents of the R1-R4 group, and respectively of the R5-R8 group, are interchangeable each other, with the proviso that the position of each radical of each of the two groups R1-R4 and R5-R8 with respect to xe2x80x94OCF2Oxe2x80x94 on the chain of the intermediate compound (VII), is the same which is occupied when the synthesis takes place according to the above scheme, and the two olefins react each in the planned steps.
In the first reaction axe2x80x2) of the above scheme a hypofluorite gas flow CF2(OF)2, suitably diluted with an inert fluid, comes into contact, in a suitable reactor equipped with outlet, on the bottom of the same (first reactor), with a flow formed by the olefin R1R2Cxe2x95x90CR3R4, optionally diluted in an inert fluid, to allow the chemical reaction axe2x80x2) with formation of the intermediate hypofluorite (VI). To favour the reaction stoichiometry the reactants must be introduced into the reactor in an about unitary molar ratio, or with an excess of CF2(OF)2. The residence time of the mixture in the reactor can range from few hundredths of second up to about 120 seconds in in function of the olefin reactivity, the reaction temperature and the presence of optional reaction solvents.
The reaction temperature can range from xe2x88x9240xc2x0 to xe2x88x92150xc2x0 C., preferably from xe2x88x9280xc2x0 to xe2x88x92130xc2x0 C.
Compound (VI) is usually not separated from the reaction crude compound and is continuously transferred in the subsequent reaction described in step bxe2x80x2).
The compound mixture coming out from the first reactor can be heated to room temperature before being fed to the second reactor.
In the second reaction bxe2x80x2) the second olefin R5R6Cxe2x95x90CR7R8 at the pure state or in solution, reacts with the compound obtained in the first reaction with formation of compound (VII).
The olefin can be continuously fed so as to maintain constant its concentration in the reactor. The temperature of the reaction bxe2x80x2) can range from xe2x88x9220xc2x0 to xe2x88x92130xc2x0 C., preferably from xe2x88x9250xc2x0 to xe2x88x92100xc2x0 C. The olefin concentration is higher than or equal to 0.01M, preferably the concentration is higher than 3M, more preferably also the pure compound can be used.
The solvents used in steps axe2x80x2) and bxe2x80x2) are perfluorinated or chlorohydrofluorinated solvents or hydrofluorocarbons. Examples of said solvents are: CF2Cl2, CFCl3, CF3CF2H, CF3CFH2, CF3CF2CF3, CF3CCl2H, CF3CF2Cl.
In the reaction cxe2x80x2) compound (VII), depending on the olefins used in steps axe2x80x2) and bxe2x80x2), upon distillation from the reaction crude compound, is subjected to dechlorination or to dehydrochlorination to obtain the vinylethers of formula (I).
This last step can be carried out by using reactions widely described in the prior art. The suitable selection of the substituents from R1 to R8 in the two olefins used in the synthesis allows to obtain the vinylethers of the present invention.
The following Examples are reported with the purpose to illustrate the invention and they do not limit the scope thereof.